[mirror config] extra rsync options (#107)

* support "rsync_options" array in config

* add test for new options

* fix tests

docs/zh_CN/workers.conf

@@ -45,6 +45,7 @@ docker_image = "tunathu/tunasync-scripts:latest"
 name = "gnu"
 provider = "rsync"
 upstream = "rsync://mirrors.ocf.berkeley.edu/gnu/"
+rsync_options = [ "--delete-excluded" ]
 memory_limit = "256M"
 
 [[mirrors]]
@@ -72,6 +73,7 @@ name = "ubuntu"
 provider = "two-stage-rsync"
 stage1_profile = "debian"
 upstream = "rsync://archive.ubuntu.com/ubuntu/"
+rsync_options = [ "--delete-excluded" ]
 memory_limit = "256M"
 
 # vim: ft=toml